borgbackup fails to build with Python 3.14.0a1.

Compiling src/borg/platform/windows.pyx because it changed.
Traceback (most recent call last):
  File "/usr/lib/rpm/redhat/pyproject_buildrequires.py", line 721, in main
    generate_requires(
    ~~~~~~~~~~~~~~~~~^
        include_runtime=args.runtime,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<11 lines>...
        config_settings=parse_config_settings_args(args.config_settings),
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/lib/rpm/redhat/pyproject_buildrequires.py", line 611, in generate_requires
    generate_run_requirements(backend, requirements, build_wheel=build_wheel,
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        read_pyproject_dependencies=read_pyproject_dependencies, wheeldir=wheeldir)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/rpm/redhat/pyproject_buildrequires.py", line 415, in generate_run_requirements
    generate_run_requirements_hook(backend, requirements)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/rpm/redhat/pyproject_buildrequires.py", line 329, in generate_run_requirements_hook
    dir_basename = prepare_metadata('.', config_settings=requirements.config_settings)
  File "/usr/lib/python3.14/site-packages/setuptools/build_meta.py", line 373, in prepare_metadata_for_build_wheel
    self.run_setup()
    ~~~~~~~~~~~~~~^^
  File "/usr/lib/python3.14/site-packages/setuptools/build_meta.py", line 318, in run_setup
    exec(code, locals())
    ~~~~^^^^^^^^^^^^^^^^
  File "<string>", line 218, in <module>
  File "/usr/lib64/python3.14/site-packages/Cython/Build/Dependencies.py", line 1134, in cythonize
    pool = multiprocessing.Pool(
        nthreads, initializer=_init_multiprocessing_helper)
  File "/usr/lib64/python3.14/multiprocessing/context.py", line 119, in Pool
    return Pool(processes, initializer, initargs, maxtasksperchild,
                context=self.get_context())
  File "/usr/lib64/python3.14/multiprocessing/pool.py", line 215, in __init__
    self._repopulate_pool()
    ~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.14/multiprocessing/pool.py", line 306, in _repopulate_pool
    return self._repopulate_pool_static(self._ctx, self.Process,
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
                                        self._processes,
                                        ^^^^^^^^^^^^^^^^
    ...<3 lines>...
                                        self._maxtasksperchild,
                                        ^^^^^^^^^^^^^^^^^^^^^^^
                                        self._wrap_exception)
                                        ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/multiprocessing/pool.py", line 329, in _repopulate_pool_static
    w.start()
    ~~~~~~~^^
  File "/usr/lib64/python3.14/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
                  ~~~~~~~~~~~^^^^^^
  File "/usr/lib64/python3.14/multiprocessing/context.py", line 300, in _Popen
    return Popen(process_obj)
  File "/usr/lib64/python3.14/multiprocessing/popen_forkserver.py", line 35, in __init__
    super().__init__(process_obj)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/multiprocessing/popen_fork.py", line 20, in __init__
    self._launch(process_obj)
    ~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/lib64/python3.14/multiprocessing/popen_forkserver.py", line 51, in _launch
    self.sentinel, w = forkserver.connect_to_new_process(self._fds)
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/usr/lib64/python3.14/multiprocessing/forkserver.py", line 85, in connect_to_new_process
    self.ensure_running()
    ~~~~~~~~~~~~~~~~~~~^^
  File "/usr/lib64/python3.14/multiprocessing/forkserver.py", line 139, in ensure_running
    listener.bind(address)
    ~~~~~~~~~~~~~^^^^^^^^^
OSError: AF_UNIX path too long

https://docs.python.org/3.14/whatsnew/3.14.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.14/fedora-rawhide-x86_64/08257958-borgbackup/

For all our attempts to build borgbackup with Python 3.14, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/package/borgbackup/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.14:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/

Let us know here if you have any questions.

Python 3.14 is planned to be included in Fedora 43.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.14.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.